1. Field of the Invention
The present invention relates to a printing apparatus and control method thereof.
2. Description of the Related Art
An inkjet printing apparatus cannot obtain a high-quality image unless a plurality of ink droplets land at correct positions on a printing medium (for example, paper), and form dots on the printing medium in a relatively correct array.
However, the ink landing position varies owing to various errors contained in the printing apparatus. To correct the ink landing position, it is well known to adjust the discharge timing.
As a method of obtaining discharge timing information for correcting the ink landing position, a technique which pays attention to overlapping of printing patterns has been disclosed (see Japanese Patent Laid-Open No. 10-329381). There has also been disclosed a technique of obtaining discharge timing information by measuring a distance between a reference pattern and an adjustment pattern (see Japanese Patent Laid-Open No. 2002-361965).
In the technique disclosed in Japanese Patent Laid-Open No. 10-329381, the printing resolution of the adjustment pattern defines a resolution which can be obtained by correction of the ink landing position. In this arrangement, the printing area becomes large when ink landing position information is obtained at high accuracy in a wide range.
The technique disclosed in Japanese Patent Laid-Open No. 2002-361965 can correct the ink landing position even if the printing area is small. However, the reference pattern and adjustment pattern are not printed at the same position on a printing medium, and are affected by variations of the ink landing position dependent on the printing position.